Abstract: The motion characteristics of characters work as a breakthrough point,the different application of octree were designed in animated automatic generative system respectively:octree is used to simplify scene modeling for flying characters which don't need to build scene modeling accurately.It is used to test intersection between models and detect collision in process of path searching for walking and crawling characters which demand high precision of scene modeling.Experiments results showed that the efficiency of scene modeling and path planning were improved and the complexity was simplified with octree.The methods could plan a more reasonable path for all kinds of characters.The results of planning path had more rationality and optimality.